fix: make sure with testing experiment config is always a struct

internal/registry/factory.go

@@ -264,7 +264,6 @@ func (b *Factory) SetOptionsJSON(value json.RawMessage) error {
 
 	// otherwise unmarshal into the configuration, which we assume
 	// to be a pointer to a structure.
-	// TODO(bassosimone): make sure with testing that b.config is always a pointer.
 	return json.Unmarshal(value, b.config)
 }
 

internal/registry/factory_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"math"
 	"os"
+	"reflect"
 	"testing"
 
 	"github.com/apex/log"
@@ -964,3 +965,20 @@ func TestFactoryNewTargetLoader(t *testing.T) {
 		}
 	})
 }
+
+func TestExperimentConfigIsAlwaysAPointerToStruct(t *testing.T) {
+	for name, ffunc := range AllExperiments {
+		t.Run(name, func(t *testing.T) {
+			factory := ffunc()
+			config := factory.config
+			ctype := reflect.TypeOf(config)
+			if ctype.Kind() != reflect.Pointer {
+				t.Fatal("expected a pointer")
+			}
+			ctype = ctype.Elem()
+			if ctype.Kind() != reflect.Struct {
+				t.Fatal("expected a struct")
+			}
+		})
+	}
+}

internal/registry/webconnectivity.go

@@ -15,11 +15,11 @@ func init() {
 		return &Factory{
 			build: func(config any) model.ExperimentMeasurer {
 				return webconnectivity.NewExperimentMeasurer(
-					config.(webconnectivity.Config),
+					*config.(*webconnectivity.Config),
 				)
 			},
 			canonicalName:    canonicalName,
-			config:           webconnectivity.Config{},
+			config:           &webconnectivity.Config{},
 			enabledByDefault: true,
 			interruptible:    false,
 			inputPolicy:      model.InputOrQueryBackend,